Combined fibre channel and sas host bus adapter

ABSTRACT

Apparatus, systems, and methods for coupling Fibre Channel (FC) storage devices and serial attached SCSI (SAS) storage device to a computer system through a single host bus adapter (HBA). The HBA includes a SAS storage controller four coupling to one or more SAS storage devices and an FC interface for coupling to one or more FC storage devices. The HBA also includes translation logic to translate information exchanged between the SAS storage controller and the FC storage device(s). Translation may include translation of addressing information between FC protocols and formats used by the SAS storage controller, may include use of a buffer to enable exchanges at different data rates, and may include use of a buffer to aggregate an inbound FC multiframe sequence into a single data buffer for use by the SAS storage controller.

BACKGROUND

1. Field of the Invention

The invention relates generally to host bus adapter (HBA) for coupling ahost computer system to peripheral devices and more specifically relatesto an HBA that couples both Fibre Channel (FC) and Serial Attached SCSI(SAS) storage device to a host computer system.

2. Discussion of Related Art

Fibre Channel has been a common standard for coupling of storage devicesto a computer system for high speed applications. SAS has been evolvingas a lower cost alternative to Fibre Channel providing similarperformance at lower costs. Further, using a SAS connection, still lowercost Serial Advanced Technology Attachment (SATA) storage devices may beused by utilizing the SATA Tunneling Protocol (STP) in the SAS family ofprotocols.

Some computing environments are migrating new storage applications tolower cost SAS/SATA architectures but still must support older, legacystorage applications operating on FC storage devices coupled through anFC communication medium. In such cases, a computing system must providetwo HBAs—one for coupling to the SAS/SATA storage devices and anotherfor coupling to the FC connected storage devices. Use of two HBAsconsumes resources in the computing system and complicates softwareapplications that may require access to both the SAS/SATA storagedevices and the FC storage devices.

Thus it is an ongoing challenge to simplify structures to support bothFC and SAS/SATA storage devices on a single computing system.

SUMMARY

The present invention solves the above and other problems, therebyadvancing the state of the useful arts, by providing a single HBA thatseamlessly supports both FC and SAS/SATA storage devices. The combinedFC/SAS/SATA HBA is adapted to support multiple SAS/SATA devices coupledto a redundant array of independent drives (RAID) controller circuit onthe HBA and also supports externally coupled FC storage devices coupledto the same RAID controller on the HBA. The FC storage devices arecoupled to the RAID controller in a manner that translates the FC dataexchanges into a SAS style of operation. The computing system mayoperate both types of storage devices through a single software (e.g.,device driver) programming interface. The computing system thusconserves resources by using only a single bus interface slot andrequiring only a single software (driver) interface to the HBA RAIDcontroller. Further, by translating the FC exchanges in operation of theHBA's RAID controller into SAS-like exchanges, all storage devicescoupled through the combined HBA may be managed transparently regardlessof the protocol and media used to couple them (FC or SAS).

In one aspect hereof, an HBA is provided for use in a computing system.The HBA includes a SAS storage controller circuit adapted to couple theHBA to a first storage device and a Fibre Channel (FC) interface circuitadapted to couple the HBA to a second storage device. The HBA furtherincludes a SAS/FC translation circuit coupled to the SAS storagecontroller circuit and coupled to the FC interface circuit. Thetranslation circuit is adapted to intercept exchanges between thestorage controller interface and the FC interface circuit and is furtheradapted to translate the intercepted exchanges between SAS protocols andFC protocols. The HBA enables an attached computer system to accesseither or both of the first storage device and the second storage deviceas a SAS compatible storage device.

Another aspect hereof provides a method operable in an HBA, the HBAincluding a Fibre Channel (FC) interface and including a serial attachedSCSI (SAS) storage controller. The method includes exchanginginformation between the SAS storage controller and a first storagedevice coupled to the HBA using a SAS protocol and exchanginginformation between the SAS storage controller and a second storagedevice through the FC interface. The method also includes translatingthe information exchanged between the SAS storage controller and thesecond storage device between FC protocols and a format used by the SASstorage controller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary computer system including acombination HBA in accordance with features and aspects hereof.

FIG. 2 is a block diagram providing exemplary additional details of thecombination HBA of FIG. 1 in accordance with features and aspectshereof.

FIG. 3 is a block diagram providing exemplary additional details of theSAS/FC translation logic of the exemplary HBA of FIG. 2 in accordancewith features and aspects hereof.

FIG. 4 is a flowchart describing an exemplary method for an HBA toexchange information with either or both of an FC storage device and aSAS/SATA storage device in accordance with features and aspects hereof.

FIG. 5 is a flowchart describing exemplary additional details of themethod of FIG. 4.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a host computer system 100 that includes acombination HBA 108 capable of coupling the host system, through asingle HBA, to both SAS/SATA storage devices 110.1 through 110.2 and toFibre Channel storage devices 112.1 and 112.2. The combined SAS/FC HBA108 may couple to the SAS/SATA storage devices 110.1 and 110.2 bystandard SAS communication media and protocols 150. In addition, theSAS/FC combination HBA 108 may coupled to FC storage devices 112.1 and112.2 utilizing standard Fibre Channel arbitrated loop (FCAL) media andprotocols 152 (or other Fibre Channel compliant media and protocols).

The combination HBA 108 permits the host computer system to utilize asingle SAS device driver 106 for coupling operating system 104 andapplication 102 to any of the storage devices (SAS/SATA/FC). By contrastto prior techniques, multiple HBAs would be required, a first forSAS/SATA storage device interaction and a second for FC storage deviceinteraction. In addition to multiple HBAs, prior techniques wouldrequire multiple device driver modules to couple the operating system104 and application 102 to the various storage devices. Still further,higher level storage management features within operating system 104would be required to interact through multiple such device drivers, eachcoupled to a corresponding type of HBA, to permit access to the varietyof storage devices (thus further complicating the storage applicationsthat may desire access to a logical grouping or volume of storagedevices that may include both SAS/SATA devices and Fibre Channeldevices).

As shown in the exemplary embodiment of FIG. 1, the SAS/SATA storagedevices 110.1 and 110.2 may be physically internal to the host computersystem 100 and coupled to HBA 108 through standard SAS internal wiringand communication media 150. Fibre Channel storage devices 112.1 through112.2 may be coupled via an external connector of HBA 108 to externalstorage devices physically present outside of host computer system 100using standard FCAL communication media 152. Those of ordinary skill inthe art will further recognize that any combination of internallyconfigured storage devices and externally configured storage devices maybe utilized with features and aspect hereof. Thus the particularconfiguration showing SAS/SATA devices internal to host computer system100 and Fibre Channel storage devices physically external to hostcomputer system 100 is intended merely as exemplary of one embodiment offeatures and aspects hereof. Still further, those of ordinary skill inthe art will readily recognize that any number of the storage devicesmay be configured in the computer system 100 limited principally byphysical connector space and logical addressing capabilities of the HBA108.

It will be recognized that combination HBA 108 advantageously conservesresources in computer system 100 by utilizing only a single host systembus connector for coupling of SAS/SATA/FC storage devices. Further,system 100 utilizing HBA 108 advantageously reduces software resourceswithin computer system 100 by utilizing a single device driver 106 forinteracting with SAS/SATA/FC storage devices.

FIG. 2 is a block diagram providing exemplary additional details of anembodiment of HBA 108 of FIG. 1. HBA 108 may include SAS storagecontroller 200. SAS storage controller 200 may be, for example, a RAIDcontroller chip adapted for interaction with SAS/SATA storage devices toprovide high performance, high reliability RAID storage managementfeatures. SAS ports 206 represent ports integrated with or coupled toSAS storage controller 204 for coupling one or more SAS/SATA storagedevices via internal cabling 150 (or via external cabling and mounting).PCI Express interface 208 may be similarly integrated within SAS storagecontroller 200 or may be coupled with storage controller 200 forpurposes of coupling HBA 108 to a PCI Express host system bus of thehost computer system utilizing HBA 108. Those of ordinary skill in theart will readily recognize that any of a variety of well-known host businterface components may be utilized for coupling HBA 108 to a hostcomputer system interface bus. PCI Express is merely shown as one commonexample of a commercially available host computer system bus.

SAS storage controller 200 is coupled with SAS/FC translation logic 202via path 250 which is, in turn, coupled with FC interface 204 via path252. FC interface 204 may be, for example, a Tachyon interface circuitas generally known and commercially available that provides FC protocolFC1 and FC2 layer logic for coupling with FC storage devices via FCcommunication media and protocol 152. The Tachyon chip is one exemplarycomponent useful for such an FC interface 204. Numerous othercommercially available FC interface components may also be utilized asFC interface 204 within HBA 108 as a matter of design choice. Storagecontroller 200 may be any suitable controller circuit including, forexample, a SAS RAID storage controller circuit such as is commerciallyavailable from LSI Corporation (see, e.g., www.lsi.com). Paths 250 and252 coupling translation logic to the SAS storage controller 200 and theFC interface 204, respectively, may be any suitable bus architecture forcoupling signals of each device to the translation logic 202. Inparticular, translation logic 202 may include suitable bus interfacelogic for coupling to each of the potentially unique bus structures onpaths 250 and 252.

SAS/FC translation logic 202 provides translation of information to beexchanged between SAS storage controller 200 and FC interface 204. Forexample, addressing information associated with FC storage devicescoupled through FC interface 204 may be translated from or intocorresponding SAS addressing information such that each FC storagedevice may be associated with a corresponding SAS address in operationof SAS storage controller 200. Further, FC frames sequences representingan FC multiframe sequence transmission in FC communications may beassembled and aggregated in a buffer within SAS/FC translation logic202. Still further, SAS/FC translation logic 202 may utilize a buffer toprovide speed matching capabilities to permit full speed operation oneither side of the translation logic 202 despite a potential differencein data rates in the design of the FC communications and that of the SASstorage controller 200 in interacting with SAS storage devices throughSAS ports 206. SAS/FC translation logic 202 therefore provides allnecessary translation of information to be exchanged such that SASstorage controller 200 may interact with Fibre Channel storage devicesas though they are other SAS storage devices. By providing suchtranslation, a host computer system device driver component, adapted forinteraction with SAS/SATA storage devices through SAS storage controller200, may also interact with Fibre Channel storage devices in essentiallythe same manner that it interacts with SAS/SATA storage devices coupledto the HBA.

FIG. 3 is a block diagram providing exemplary additional details of thestructure of FC translation logic 202 of FIG. 2. Translation logic 202may include SAS/FC addressing translation logic 300 for translatingbetween FC protocol addressing standards and SAS protocol addressingstandards in exchanges between the SAS storage controller 200 and FibreChannel interface 204 of FIG. 2. Addressing translation 300 may use, forexample, a SAS/FC address map table 301 to map between FC addresses andSAS addresses for each FC storage device accessed by the SAS storagecontroller. Specific logic for mapping between FC and SAS addresses fora particular FC storage device will be readily apparent to those ofordinary skill in the art as a matter of design choice. Further, thoseof ordinary skill in the art will readily recognize numerous well knowntechniques to initially load the map table 301 with the addresses to bemapped in exchanges between the SAS storage controller and the FCstorage devices.

Translation logic 202 may also include a SAS buffer 306 for receivingand transmitting SAS frames or other SAS information between thetranslation logic 202 and the SAS storage controller coupled via path250. SAS controller interface bus logic 308 adapts signals within thetranslation logic 202 for exchange with the signals used by the SASstorage controller coupled via path 250. The SAS buffer 306 may providespeed matching capabilities to allow for different operating speeds(based on data rates of the SAS storage controller relative to the FCstorage devices). In addition, SAS buffer 306 may be used to assembleand disassemble SAS frames and other information exchanged betweentranslation logic 202 and the SAS storage controller.

Still further translation logic 202 may include FC buffer 302 forreceiving and transmitting FC frames or other FC information between thetranslation logic 202 and the FC storage devices coupled via path 252.FC interface bus logic 304 adapts signals within the translation logic202 for exchange with the signals used by the FC interface coupled viapath 252. The FC buffer 302 may provide speed matching capabilities toallow for different operating speeds (based on data rates of the SASstorage controller relative to the FC storage devices). In addition, FCbuffer 302 may be used to assemble and disassemble FC frames and otherinformation exchanged between translation logic 202 and the FC storagedevices. In particular, FC buffer 302 may serve as a multiframe sequencebuffer used to receive and aggregate multiple FC frames that arereceived as a multiframe sequence into a single buffer for transfer tothe SAS storage controller.

Those of ordinary skill in the art will recognize that SAS buffer 306and FC buffer 302 may be physically implemented as a single memorylogically divided into portions for each purpose in the translationlogic 202 or may be implemented as distinct memory subsystems as amatter of design choice.

FIG. 4 is a flowchart describing an exemplary method in accordance withfeatures and aspects hereof operable within a combined SAS/SATA/FC HBA.Step 400 determines whether a desired exchange is directed between aSAS/SATA storage device and the SAS storage controller or is directedbetween an FC storage device and the SAS storage controller. If thelatter, step 402 translates appropriate information for exchange betweenthe FC storage device and the SAS storage controller. As noted above,such translation may include translation of addressing informationbetween that used by the FC protocols and the appropriate addressinginformation format for the SAS storage controller. In addition, thetranslation may include aggregation of FC frames representing an FCmultiframe sequence into a single buffer for transmission to the SASstorage controller. Still further, translation may include use of abuffer for speed matching to assure independence of the operating speedof the FC protocol and media in communicating with an FC storage deviceand the standard data rates associated with the SAS storage controller.

If step 400 determines that the desired exchange is between a SAS/SATAstorage device and the SAS controller, step 406 performs the normalexchange operations between the SAS storage controller and the SAS/SATAstorage device. Such normal SAS/SATA information exchanges are wellknown to those of ordinary skill in the art and therefore need not befurther detailed here.

FIG. 5 is a flowchart providing exemplary additional details of theoperation of steps 402 and 404 of FIG. 4 to exchange information betweenan FC storage device and the SAS storage controller of the HBA. Step 500first determines whether the exchange is directed from the SAScontroller to the FC storage device or from the FC storage device to theSAS storage controller. In the case of an exchange directed from the SASstorage controller to the FC storage device, step 502 translates the SASaddressing information into corresponding addressing information for usein the FC frames to be sent to the FC storage device. As noted above,the address translation may include both translation of the particularformat used for FC addressing as compared to SAS protocol addressing aswell as translation of a logical address used by the SAS storagecontroller into a corresponding physical address of the FC storagedevice. Thus, the SAS storage controller may address each FC storagedevice as though it is another SAS/SATA storage device and appropriatetranslation will be performed by step 502 within the translation logic.The frame/frames as translated to use FC addressing may be stored in abuffer for transfer to the FC storage device at appropriate data ratesfor the FC device. Step 504 then transmits the SAS data with associatedtranslated addressing information as one or more FC frames directed tothe FC storage device through the FC interface of the HBA.

Where step 500 determines that the transmission is directed from the FCstorage device to the SAS storage controller of the HBA, step 510 firstdetermines whether the received FC frame represents a portion of amultiframe sequence or represents a single FC frame. If the FCtransmission represents a single FC frame, step 512 translates the FCaddressing information from the single FC frame into the correspondingappropriate format for the SAS storage controller. Step 514 then storesthe received FC frame data in a buffer for transmission to the SASstorage controller. Step 516 then signals the SAS storage controllerthat data is ready to be retrieved from the buffer. The SAS storagecontroller may then retrieve the data sent from the FC storage device ina manner consistent with its retrieval of data from SAS storage devices.

If step 510 determines that a received FC frame is part of a multiframesequence, step 520 aggregates the received frame in a buffer to form asingle buffer of data for transmission to the SAS storage controller.Step 522 then determines whether this FC frame represents the last frameof the multiframe sequence. If not, processing completes awaitingreceipt of the last such frame. If the received FC frame is the lastframe of the multiframe sequence, step 524 translates the FC addressinginformation associated with the FC multiple frames into appropriateformat for use by the SAS storage controller. Step 526 then stores thedata in the buffer for transmission to the SAS storage controller. Step516 then signals the SAS storage controller, as described above, thatdata is ready to be retrieved in the buffer.

Those of ordinary skill in the art will readily recognize numerousadditional and equivalent steps that may be performed in the methods ofFIGS. 4 and 5. Such additional and equivalent steps are omitted hereinfor simplicity and brevity of this discussion. Thus methods of FIGS. 4and 5 are intended merely as representative of exemplary embodiments ofmethods in accordance with features and aspects hereof operable within acombined HBA capable of communicating with both SAS/SATA storage devicesand with FC storage devices. Still further, the methods described inFIGS. 4 and 5 may be implemented as custom electronic circuits such asin an ASIC or field programmable gate array (FPGA) and/or may beimplemented as suitably programmed instructions operable in anappropriate general or special purpose processor.

While the invention has been illustrated and described in the drawingsand foregoing description, such illustration and description is to beconsidered as exemplary and not restrictive in character. One embodimentof the invention and minor variants thereof have been shown anddescribed. Protection is desired for all changes and modifications thatcome within the spirit of the invention. Those skilled in the art willappreciate variations of the above-described embodiments that fallwithin the scope of the invention. As a result, the invention is notlimited to the specific examples and illustrations discussed above, butonly by the following claims and their equivalents.

1. A host bus adapter (HBA) for use in a computing system, the HBAcomprising: a serial attached SCSI (SAS) storage controller circuitadapted to couple the HBA to a first storage device; a Fibre Channel(FC) interface circuit adapted to couple the HBA to a second storagedevice; and a SAS/FC translation circuit coupled to the SAS storagecontroller circuit and coupled to the FC interface circuit, thetranslation circuit adapted to intercept exchanges between the storagecontroller interface and the FC interface circuit, the translationcircuit further adapted to translate the intercepted exchanges betweenSAS protocols and FC protocols, wherein the HBA enables an attachedcomputer system to access either or both of the first storage device andthe second storage device as a SAS compatible storage device.
 2. The HBAof claim 1 wherein the first storage device is a SAS storage device andthe second storage device is an FC storage device.
 3. The HBA of claim 1wherein the first storage device is a serial advanced technologyattachment (SATA) storage device and the second storage device is an FCstorage device.
 4. The HBA of claim 1 wherein the SAS storage controllerincludes: a redundant array of independent drives (RAID) controller, andwherein the RAID controller is adapted to enable an attached hostcomputer system to access a RAID logic volume comprising portions thefirst storage device and/or portions of the second storage device. 5.The HBA of claim 1 wherein the SAS/FC translation circuit includes:address translation logic to translate between FC addressing informationused by the FC interface circuit in accessing the second storage deviceand SAS addressing information used by the SAS storage controller. 6.The HBA of claim 1 wherein the SAS/FC translation circuit includes: abuffer adapted to receive FC inbound frames from the second storagedevice wherein the buffer is used to aggregate inbound data contained inmultiple received FC inbound frames received through the FC interfacecircuit to provide a single buffer of inbound data to the SAS storagecontroller circuit.
 7. The HBA of claim 1 wherein the SAS/FC translationcircuit includes: a buffer adapted to receive FC inbound frames from thesecond storage device, wherein the FC interface circuit is adapted toreceive inbound FC frames at a data rate higher than the data rate ofthe SAS storage controller, and wherein the SAS storage controller isadapted to receive inbound data from the FC inbound frames through thebuffer.
 8. A method operable in a host bus adapter (HBA), the HBAincluding a Fibre Channel (FC) interface and including a serial attachedSCSI (SAS) storage controller, the method comprising: exchanginginformation between the SAS storage controller and a first storagedevice coupled to the HBA using a SAS protocol; exchanging informationbetween the SAS storage controller and a second storage device throughthe FC interface; and translating, within the HBA, the informationexchanged between the SAS storage controller and the second storagedevice between FC protocols and a format used by the SAS storagecontroller.
 9. The method of claim 8 wherein the step of translatingfurther comprises: translating address information between FC protocoland the format used by the SAS storage controller.
 10. The method ofclaim 8 wherein the step of translating further comprises: translatingbetween FC addressing information used by the FC interface circuit inaccessing the second storage device and SAS addressing information usedby the SAS storage controller.
 11. The method of claim 8 wherein thestep of translating further comprises: storing inbound FC multiframesequences in a buffer adapted to receive FC inbound frames from thesecond storage device to aggregate inbound data contained in multiplereceived FC inbound frames to provide a single buffer of inbound data tothe SAS storage controller.
 12. The method of claim 8 wherein the stepof translating further comprises: storing inbound FC frames from thesecond storage device in a buffer, wherein the FC inbound frames arereceived at a data rate higher than the data rate of the SAS storagecontroller, and wherein the SAS storage controller is adapted to receiveinbound data from the FC inbound frames through the buffer.